1 Ferguson's men make hard work of easy test

Before kick-off Sir Alex Ferguson was in confident mood, telling the United programme: "As regards tonight I feel the advantage has swung our way bringing West Ham back to Old Trafford and with the incentive of another home tie against Fulham [as it is] or Blackpool if we can defend a bit better this time. You can't ask more from a cup draw." You also cannot hope for more than opponents who turn up and offer the kind of insipid test West Ham did as a barrier to the next round. Yet, although this 1-0 win did not reflect United's supremacy, it does show how much hard work they made of progressing. Ferguson and senior players, including Rio Ferdinand, have all mentioned how the club has not won this trophy since 2004 and how they want to change this. Not only is this FA Cup quest still possible, so is a repeat of the 1999 treble.

2 United's No10 is back

"Rooney Rooney!" was the greeting as the forward trotted over to take a corner from the left on the half-hour. Robin van Persie may be Old Trafford's latest darling but warmth is retained for the 27-year-old who had not featured since a 1-1 draw at Swansea City in the league, having injured a knee in training on Christmas Day. This shaking off of the rust before Sunday's trip to Tottenham had a promising start for Rooney, for which he had Javier Hernández to thank (although he did miss a second-half penalty). On nine minutes the Mexican took on Anderson's skimmed pass into the area, looked up, then squared the ball to Rooney, who slid home. This was greeted by the touching sight of him hailing the heavens with a gesture akin to Frank Lampard's, which was perhaps in memory of Rosie McLoughlin, the adopted sister of his wife Colleen, who died recently.

3 Nani as erratic as ever

What might Wilfried Zaha's potential arrival mean for the Portuguese wing man? The second United man making his comeback on the night, Nani's absence had been far longer than Rooney's as it stretched back to the 3-1 win at Braga in early November, when he suffered a hamstring injury. Zaha, of course, is only raw potential and, if he does join, may well be loaned straight back to Crystal Palace for the remainder of the season. But Nani's erratic form, when fit, means he may be under threat and he was again indifferent on a night when West Ham allowed him enough room to flourish. There was the odd flicker of stardust: one reverse pass with the inside of his right heel to Antonio Valencia was executed perfectly and he might have had United's second on 29 minutes when he blazed a shot across the West Ham goal that required Daniel Potts to make a last-ditch clearance.

4 Allardyce's tactics offer limited test of youngsters

Jonny Evans apart – a hamstring problem ruled him out – the back four of Rafael da Silva, Chris Smalling, Phil Jones and Alexander Buttner provided a peek at the future Reds defence. The problem with gauging how fit for purpose they may be was the one-note attacking tactic of West Ham's manager, Sam Allardyce, who informed his side to sling in high balls whenever they could. Rafael et al did, though, struggle with this, as United had in the first edition of the tie 11 days previously. Then, West Ham's goals in the 2-2 draw both came from crosses lifted into the area, of which Ferguson noted before this return: "We really should be doing better in that kind of situation. I couldn't believe it when they scored their second with exactly the same approach [as the first]. Talk about deja vu." Gary O'Neil twice placed free-kicks at United that they struggled to repel, before, after the break, Smalling struggled to deal with Matt Taylor's corner.

5 Hammers sometimes looked a man short

For the 1,400 travelling fans from east London this quickly became an occasion with a training-ground feel due to the quietness of their opposing number. This had the West Ham fans taunting them with chants that included "There's only one Carlos Tevez", who played for each club and who scored here to keep the Hammers up in 2007, and, in the second half, "We're going to score in a minute". While they nearly did when Rafael cleared from close to his line on the hour, at times West Ham looked to have only 10 players. When United moved forward the visitors effectively featured a five-man defence as Potts and Jordan Spence dropped from wing-back to join James Tomkins, Alou Diarra and Winston Reid. The problem was the midfield three that this left – Gary O'Neil, Matt Taylor and Mohamed Diamé – were unable to close down United and were overrun.